BEIJING – Dara Torres had just become the oldest swimmer to win an Olympic silver medal, but her body language was still apologetic as she climbed out of the pool today alongside rivals young enough to be her daughters.

“One hundredth,” she said, shrugging her broad shoulders, as she smiled at a group of supporters in the stands at the Water Cube.

It was testimony to how driven Torres was in her unlikely and ultimately successful quest to return to the Olympics.

At age 41, the graduate of Westlake School for Girls (now Harvard-Westlake of Studio City) did not just believe in her chances to take part in the Games; she believed in her chances to win.

She had concentrated the bulk of her energy on this 50-meter freestyle, withdrawing from the 100 free before the Games to focus on her best chance. She qualified for the final with the fastest time and earned the right to start in lane four.

But though Torres’ American teammate Michael Phelps managed to win by one-hundredth of a second on Saturday to keep his historic streak alive in Beijing, Torres ended up losing by the same fractional amount to Germany’s Britta Steffen.

“I’m competitive, so I wanted to win gold in the 50,” Torres said. “I gave it my best shot and I’m thinking maybe I shouldn’t have filed my nails last night.”

Torres appeared to have a slight lead as she stroked powerfully toward the finish in this one-lap sprint, but as she and Steffen closed in on resolution, Torres chose to finish off her last stroke by gliding with her right arm. Steffen’s more aggressive finish with her left arm was just enough to win and complete a sprint double here in Beijing, become the first woman to do so since Dutch star Inge de Bruijn in 2000.

Steffen’s time of 24.06 seconds was an Olympic record. Torres’ finished in 24.07, which was an American record and a personal best: 18 hundredths of a second faster than she swam at the U.S. Trials earlier this summer in Omaha, Neb.

More remarkably, it was more than half a second faster than the time she swam in her last Olympic 50, when she took the bronze in 2000 at age33.

Later, Torres anchored the United States’ silver-medal effort in the women’s 400 medley relay. The American team of Torres, Rebecca Soni (USC), Natalie Coughlin and Christine Magnuson clocked 3:53.30 – second to Australia’s world-record setting time of 3:52.69.

Steffen, who won the 100 free Friday, is 24. Cate Campbell, the Olympic debutante from Australia who won the bronze in 24.17 seconds, turned 16 in May and seemed less amazed by Torres’ age than by the fact that Torres already has a 2-year-old daughter.

“Most of us girls we have to stop our sport so we can start a family, but for her to have a family and still get back in and win the silver medal is just absolutely incredible,” Campbell said.

Torres has retired twice, but her latest comeback started last year when, already in prime shape, she decided that she wanted a greater challenge. She now has two more Olympic medals to bring her career total to 12, tying American Jenny Thompson for most by a female swimmer.

Her success in Beijing is the latest exclamation point in what has been a remarkable summer for middle-aged sports figures with 50-year-old Nancy Lieberman returning to play in a WNBA Game and with 53-year-old Greg Norman leading after three rounds at the British Open.

But sprint freestyling is hardly golf. It requires controlled power and explosion: qualities that logically would favor the younger set. Pieter Van den Hoogenband, the 30-year-old Dutch champion, retired earlier this week after failing to win a medal in the men’s 100 free, claiming that he could no longer keep up with the younger set.

Torres, as it turned out, could only not keep up with Steffen. And she faltered by the slimmest margin in swimming.

Also, Ous Mellouli (USC) won Tunisia’s first Olympic swimming gold medal, denying Aussie Grant Hackett’s bid for a third consecutive title in the men’s 1,500 freestyle.

Mellouli held off Hackett in the closing meters of the grueling race today, finishing in 14:40.84. Hackett earned the silver in 14:41.53, well off his 7-year-old world record.

Ryan Cochrane of Canada took the bronze in 14:42.69.

Mellouli, an All-American with the Trojans, is coming off a suspension after testing positive for adderall at a U.S. Open meet in November 2006.